Here take back the stuff that I am, nature, knead it back into the dough of being, make of me a bush, a cloud, whatever you will, even a man, only no longer make me.

In the world we live in, one fool makes many fools, but one sage only a few sages.

Be attentive, feel nothing in vain, measure and compare: this is the whole law of philosophy.

Even truth needs to be clad in new garments if it is to appeal to a new age.

A schoolteacher or professor cannot educate individuals, he educates only species.

Perhaps in time the so-called Dark Ages will be thought of as including our own.

If we make a couple of discoveries here and there we need not believe things will go on like this for ever. Just as we hit water when we dig in the earth, so we discover the incomprehensible sooner or later.